Evoked potential asymmetries and behavioral responses to consonant-vowel stimuli presented dichotically and diotically

Cortical auditory-evoked potentials (AEP's) were recorded simultaneously with the collection of behavioral responses to consonant-vowel stimuli presented both dichotically and diotically in a group of 16 right-handed normal females. During dichotic listening, the mean N1-P2 component of the AEP's recorded over the temporal region of the left hemisphere was found to be significantly larger in amplitude than the mean recorded over the homologous area of the right hemisphere. No significant amplitude differences were found for any AEP component during diotic listening. The latencies of AEP components revealed no systematic trend across hemispheres during either dichotic or diotic listening. The mean amplitude of N1, and the mean peak-to-peak amplitudes of P1 and N1 and N1-P2 were significantly larger over the right hemisphere during dichotic listening than during diotic listening, a result opposite to that expected if suppression of right hemisphere activity had occurred during dichotic testing. Correlation analyses revealed no significant relationships between hemispheric differences in AEP's, a measure of strength of handedness, and a measure of right-ear advantage during dichotic listening.